Databases 2 and 3 are slow, there's a lot of waits on latches coming free.

So yes there's a memory issue, but how do I find out the amount of memory on the box, Grid reports 8GB, but whats the difference between virtual and real? I thought virtual was when the system starts swapping out etc.

Basic and stupid question maybe, but after some help.

04-04-2005, 10:09 AM

anandkl

Hi,
Real memory is the memory from RAM(Random access memory) while virtual memory is the amount of space allocated on the system hard disk.

When ever a process runs our of memory from RAM, it will swap(start) to use the virtual memory. If there is too much swaping then your application on the server will perform slowly.

Hope your got the difference.

regards
anandkl

04-04-2005, 10:24 AM

davey23uk

Re: top command on hp-ux

Quote:

Originally posted by bazza

So yes there's a memory issue, but how do I find out the amount of memory on the box, Grid reports 8GB, but whats the difference between virtual and real? I thought virtual was when the system starts swapping out etc.

Basic and stupid question maybe, but after some help.

dmesg | grep Phy
cat syslog | grep Phy

04-05-2005, 07:17 AM

bazza

Hi,

thanks for the help.

Anandkl, yep, that was pretty much my understanding.

Davey, unfortunately I can't access the syslog.

After the system consumed all the swap space yesterday(eek), the sysadmin guys added more swap space, but knowing this would not cure the performance issue, I dropped the SGA on datbase 1 by 1Gb, and now databases 2 & 3 are noticeably quicker. No doubt due to the fact the SGA's are no longer running off the swap space. Database1 is also fine, the sga was seemingly oversized.

But back to my original question, if Grid reports back 8Gb of memory, and the sysadmin guys swear the box has 8Gb of RAM, why do I see in top this figure of 5.7Gb of 'real' memory?